Here are some possible origins:
* Toponymic: It could derive from the Spanish word "sala", meaning "hall" or "room." In this case, it might have originally referred to someone who lived in a specific house or building with a notable hall or room.
* Occupational: It could be related to the occupation of "salar", which means "to salt" or "to preserve with salt." This suggests that the surname might have been given to someone who worked in the salt trade or as a salter of goods.
* Patronimic: In some cases, it may be a patronymic surname, meaning it was derived from a given name. For instance, it could have originated from the given name "Salas", which might have been a nickname or a shortened form of another name.
* Place of Origin: As a toponymic surname, it may be associated with specific places named "Salas" in Spain. There are several towns and villages with this name, including Salas de los Infantes in Burgos and Salas in Asturias.
Determining the exact origin of a specific family's Salas surname would require genealogical research, looking at family history, historical records, and geographic locations.
It's important to remember that surname origins can be complex and vary depending on the individual family's history.